1. Technical Field
The present invention relates in general to and, in particular, to an improved system, method and apparatus for an aircraft having counter-rotating, ring-wing rotors that are driven by engines located at their wing tips.
2. Description of the Related Art
Some types of aircraft missions require extended flight time endurance (e.g., continuous flight exceeding days, weeks or conceivably years), preferably without refueling, and the capacity to perform at high altitudes. Such missions include operations like reconnaissance, weather surveillance, communications relay, scientific observation and military operations.
Historically, these types of flight missions have been addressed by using lighter-than-air vehicles (e.g., dirigibles) and satellites instead of airborne, heavier-than-air vehicles. However, lighter-than-air vehicles tend to operate at low speeds and have difficulty with high winds. They also require special handling and large hangers for maintenance or storage. Furthermore, satellites are extremely expensive, cannot launch on short notice, and are limited in their ability to relocate to another area of interest.
Recent attempts at heavier-than-air, long endurance, high altitude air vehicles have employed wings that have large span, high aspect ratios. These designs tend to be fragile and difficult to control. Such aircraft also have had numerous difficulties with structural deflections and other types of failures when encountering wind gusts or higher than expected loads. In addition, these designs require long runways and ideal weather conditions for both launch and recovery.
Thus, these types of missions tend to be addressed by using lighter-than-air vehicles. To date there is no heavier-than-air solution that adequately addresses the performance criteria required for these operations. Although prior art aircraft are workable for long endurance missions, an improved solution that overcomes the limitations and problems associated with those designs would be desirable.